At the beginning of the year, the public learned about the “revolutionary” battery of the Finnish startup Donut Lab, a solid-state solution for electric motorcycles and cars, with phenomenal characteristics and allegedly already ready for serial production. The Finns claimed that their battery provides an energy density of up to 400 Wh/kg, that it can be charged to full capacity in just five minutes, and that it is designed to withstand up to 100,000 charging cycles with minimal loss of capacity. As expected, such claims were met with skepticism in most of the industry, but the Finns are sticking to their story – and now they are fighting back.
“I Donut Believe”
They launched the website I Donut Believe, where they will successively post evidence for their claims. They will do this by releasing a video every week, which will show that their battery really has the features they announced at CES. The company’s chief executive officer, Marko Lehtimäkinoted in the first video that the reaction was expected, drawing a parallel to the launch of their electric motor a year earlier, which was also greeted with disbelief before it entered real-world use.
Their strategy, he says, was to deliberately wait until the results of external testing were released so that critics would have their say before being presented with the facts. The company has engaged the VTT Technical Research Center of Finland, a respected national research institute, to carry out independent measurements and verification of the battery’s characteristics, and the results will now be published gradually. At the same time as the launch of the project, the first video evidence was published – the results of testing the speed of charging the battery.
The first proof – fast charging
The Donut Battery, as shown, allows for extremely fast charging without the risk of overheating, even in scenarios that simulate poor cooling inside the battery pack. During the tests, different charging rates were used, whereby a rate of 5C (1C means charging with a current that fully charges the battery in exactly one hour, 5C is therefore five times stronger current) enabled reaching 80% capacity in less than 10 minutes. Even more impressive results were recorded at the 11C rate, where the battery reached the same percentage of charge in less than 5 minutes. Admittedly, the battery heated up to over 60°C, but Donut will rise to that.
In addition to speed, the key advantage of this technology is the simplified architecture of the battery packs. Unlike conventional solutions that require strongly “clamped” cells due to their expansion during charge and discharge cycles, Donut’s battery eliminates these mechanical requirements. This could lead to lighter, cheaper and more robust systems for electric vehicles in the future, maintaining high energy density without the need for complicated active temperature management systems.
The I Donut Believe video series will follow the step-by-step verification process, from safety tests to industrial scale-up, seeking to prove that the technology, which was thought to be impossible, already exists in functional vehicles.
The next video will be released in a week.